Phenolic resins are synthetic materials that vary greatly in molecular structure. This variety allows for a multitude of applications for these resins; for example, use as a curing agent and/or to prepare the corresponding epoxy, cyanate and/or allyl thermosettable resins. These curing agents and/or resins can provide enhanced physical and/or mechanical properties to a cured composition, such as increased glass transition temperature (Tg). To achieve improved properties, however, would require the resin to have a high level of functionality (i.e., chemical groups available for cross linking). As the level of functionality increases in these resins, so does their molecular weight. As the molecular weight increases, so does the melt viscosity of the resin, which can lead to difficulties in using such resins. Thus, work has been conducted on the preparation of the aldehydes of CDDT, which can be further manipulated to create new monomers, oligomers and/or polymers.
Hydroformylated CDDT has been a synthetic target for years because it is envisioned as useful in the preparation of polymers. However, hydroformylation of CDDT results in a mixture of mono, bis, and triformylated product, typically with the mono or bis formylated product dominating the product mixture. The triformylated product may be prepared, but in very poor yields. It is also very difficult to separate the mono, bis, and trialdehydes.
U.S. Pat. No. 3,089,904 used a cobalt catalyst to hydroformylate CDDT and while the desired products were the mono and bis formylated compounds, the triformylated compound may also have been prepared, possibly as a minor component.
U.S. Pat. No. 3,184,432 described the hydroformylation of CDDT using cobalt based catalysts and the conversion of the resulting mono, bis, or trialdehydes to the corresponding mono, bis, or trialcohols. The trialcohol was not isolated.
U.S. Pat. No. 3,312,742 disclosed the hydroformylation of CDDT using palladium or cobalt based compounds in conjunction with Adkins catalyst and the isolation of the resulting mono alcohol or mono formylated products.
U.S. Pat. No. 4,251,462 taught the hydroformylation of CDDT using a combination of a rhodium catalyst and a dicobalt catalyst to generate mono, bis and trialdehydes. Example 3 in this patent reported the preparation of a hydroformylated mixture comprising 13% bis aldehyde and 85% trialdehyde (as measured by gas chromatography; the aldehydes do not appear to have been separated), where the reaction was run at 160° C. and >4000 psig using 500 ppm rhodium catalyst. The aldehydes of this patent were then converted to the amines by reductive amination.
U.S. Pat. No. 5,138,101 disclosed an extraction method that enabled the separation of product of a rhodium catalyzed hydroformylation of CDDT from the rhodium containing reaction mixture. Two different hydroformylation reactions were run. In both reactions (see reference examples 2 and 15), mono, bis and triformylated products were formed, and in both reactions, the bis formylated compound was the major product, followed by the mono formylated compound, and then the triformylated product (amounts were based on GLC analysis of the reaction mixture.) Both reactions were also run at 125° C. and approximately 260 psi. After cooling, the reaction mixture was then extracted with an alcohol and water extraction mixture that preferentially extracts the products of the hydroformylation reaction from the rhodium containing reaction mixture.
U.S. Pat. No. 6,252,121 used phase separation to selectively separate the cyclic hydroformylation product from the reaction mixture and then distilled the product. Neither the hydroformylation of CDDT nor the purification of the resulting products was described.
U.S. Pat. No. 7,683,219 conducted a hydroformylation reaction in the presence of an aldehyde, which facilitated the phase separation of the hydroformylation product from the reaction mixture. Neither the hydroformylation of CDDT nor the purification of the resulting products was described.
Current methods of hydroformylating CDDT preferentially form the mono and bis aldehydes; the trialdehyde, if formed, is a minor product. The resulting products must then be separated, which is not a simple task. Or, higher yields of the trialdehyde may be formed, but under very forcing conditions using high temperature and pressure.
It would be beneficial to be able to prepare the trialdehyde of CDDT in high yield using mild conditions. This would minimize the need to purify the resulting product mixture, and facilitate the preparation of derivatives thereof for use in the preparation of monomers, oligomers, and polymers.